1. Field of the Invention
The present invention relates generally to the processing of semiconductor substrates, and relates more particularly to apparatuses for gripping an edge of a semiconductor substrate on a robot blade.
2. Background of the Related Art
Semiconductor substrate processing is typically performed by subjecting a substrate to a plurality of sequential processes to create devices, conductors and insulators on the substrate. Each of these processes is generally performed in a process chamber configured to perform a single step of the production process. In order to efficiently complete the entire sequence of processing steps, a number of process chambers are typically coupled to a central transfer chamber that houses a robot to facilitate transfer of the substrate between the process chambers. A semiconductor processing platform having this configuration is generally known as a cluster tool, examples of which are the families of AKT PECVD, PRODUCER®, CENTURA® and ENDURA® processing platforms available from Applied Materials, Inc., of Santa Clara, Calif.
Generally, a cluster tool comprises a central transfer chamber generally surrounded by one or more process chambers. The process chambers are generally utilized to process the substrate, for example, performing various processing steps such as etching, physical vapor deposition, ion implantation, lithography and the like. The transfer chamber is typically coupled to a factory interface that houses a plurality of removable substrate storage cassettes, each of which houses a plurality of substrates. To facilitate transfer of a substrate between a vacuum environment of the transfer chamber and a generally ambient environment of the factory interface, a load lock chamber is disposed between the transfer chamber and the factory interface.
A substrate transfer robot is disposed in the cluster tool and used to transfer substrates between the process and load lock chambers. Proper positioning of the substrate on the blade of the transfer robot is critical to ensure that the substrate does not become damaged or misaligned during transfer to process chambers and to achieve repeatable processing results. Thus, the manner in which the transfer robot contacts and positions the substrate on the robot blade may affect the final processing results.
Existing methods for centering a substrate on the robot blade are typically passive in nature (e.g., in some embodiments, the substrate sits in a pocket in the blade or compensate for misalignment by altering the motion of the motor). While these methods have generally proven to be reliable and repeatable, processes directed at reducing dimensions during device fabrication are increasingly demanding finer, more accurate and repeatable substrate placement on the blade to ensure robust processing results. As such, it is desirable that more active positioning mechanisms be developed that are capable of accurately centering a substrate on a blade without damaging the substrate itself.
Therefore, there is a need for an improved apparatus for positioning a substrate on a robot blade.